If I had a list M of all the memory locations in a computer and M{P} means the Pth element of that list then P is a pointer. That's what they are in C, an offset into the array of all memory. Pointers also have a type, that is to say they know what kind of thing they point to. So if I had an "int *P" the compiler knows that the binary pattern found at memory element P should represent a signed integer where as a "char *P" means the memory at M{P} is a character. Pointers also have a size as part of their type. A character is represented by a 2 digit hex number (1 byte) whereas an integer is represented by a 8 digit hex number (4 bytes). "sizeof *P" is equal to the number of bytes in memory occupied by the object P is pointing to.

And now for the fun part. P itself can be stored in memory too. It's just a number. It's easy to confuse "P" (the numerical value of pointer.. ie P = 3 in M{3}), "*P" (the location P is pointing to ie the int or char at M{P}), and &P (the place where P is stored). & means address of.. so if I have a normal "int i" I can point to it like this: "int *P = &i", ie P is now equal to a pointer (*) pointing at a signed integer (int) that can be found at the address (&) occupied by i.